[PATCH 0/3] arm64: dts: rockchip: Change gmac phy-mode to rgmii-id for rk3576 board

[Andrew Lunn]

> > That allows using standard properties in DT instead of vendor
> > specific "rx_delay"/"tx_delay". This results in a much better board
> > description and shows how far boards derive from the the standard
> > 2ns (which can use rgmii-id without any extra delay specification).
> > 
> 
> Oh, your approach was also my initial thought.
> 
> I first asked whether it would be more appropriate to implement this
> in the PHY or in the GMAC, and Andrew told me it should preferably be 
> done in the PHY. But I'm not sure whether all PHYs support this
> operation.
> 
> Andrew, would it be possible to implement this in the GMAC for cases
> where the PHY does not support it? Thanks.

As i commented to one of the patches, the PHY will be adding 2ns by
default when 'rgmii-id' is used. If you read the RGMII standard, you
also see there is quite a wide tolerance for these delays. So unless
there is a badly designed PCB which needs something well away from
2ns, i don't think it is necessary.

     Andrew